As advances have been made in the quality and energy efficiency of light emitting diodes (LEDs), the production cost of LEDs has gone down, and LEDs are being commonly used in a wide variety of area lighting applications. Initial efforts to incorporate LEDs into lighting fixtures have involved retrofitting LEDs into conventional luminaires or onto or into the shape of conventional lighting lamps.
More recently, luminaires are being designed to account for the function and specifications of LEDs. LEDs are typically combined together in arrays onto printed circuit boards (PCBs) for ease of handling and modularity. Assembling the LEDs and the PCBs into a housing or luminaire can require precise positioning of the individual LEDs and/or the PCBs to achieve the desired array or required lighting effects from the plurality of LEDs and their associated optics or reflectors. Retrofitting LEDs into an existing luminaire or housing can raise issues related to positioning and securing the LEDs or PCBs into the housing or luminaire, to providing the correct and adequate power and controls for the LEDs, and to maintaining the appropriate appearance and aesthetics of the luminaire.
An LED emits produced light in a lambertian distribution. To control and direct this light, a means of reflecting or refracting (bending) the light rays from the LED is typically used. A typical refractor is an optic or lens that is associated with one or a plurality of the LEDs, to bend the emitted light into a desired direction or directions, or into a particular light pattern. An optic typically transmits all of the light emitted from the LED, therefore allowing the optimum opportunity to direct and control the light. Various reflector devices have been employed, each associated with one or a plurality of the LEDs. A reflector can be positioned over a single LED, to shape the emitted light that reflects off of its surface into a desired direction or pattern. Other reflectors can be positioned adjacent a plurality of LEDs to reflect light more generally from the group of LEDs.
In addition to controlling and directing the light emitted from each LED, it is desirable to control and direct the orientation of one or more LEDs, such as an array or matrix of LEDs, into a particular shape or pattern, or into a particular one or more directions. One means of directing light emitted from an array of LEDs arranged on a strip is disclosed in US Publ. 2007-0064425, which employs rotating assemblies to rotate the strips along the main axis thereof.
An LED generally includes a diode mounted onto or formed in a die or chip (collectively referenced as “die” hereinafter for simplicity). The diode is then surrounded by an encapsulant. The die receives electrical power from a power source and supplies power to the diode. The die can be mounted in a die support. To produce a brighter LED, generally, more power is delivered to the LED. Many LED lighting systems dissipate heat through a different heat transfer path than ordinary filament bulb systems.
A typical means of dissipating heat from an LED lighting system includes a heat sink adjacent to the source of heat having one or more Surfaces, and a means for dissipating heat, such as a plurality of fins or ribs which project outwardly substantially normal to the plane of the surface(s). The heat sink surface(s) and the surface of the fins provide a flow path surface over which a fluid, most likely air, will flow to facilitate heat dissipation. The fins increase the surface area of the heat sink for conducting heat from the heat sink to the air. Examples of such heat sinks with fins are shown in U.S. Pat. Nos. 6,864,513 and 7,255,460, and US Publ 2007-0041220.
Despite the continued progression of new and improved LED luminaires, there remains a need to provide improved, long-life LEDs lighting fixtures for use on illuminating work and facilities spaces.